This invention is related to an implantable electrode system, and more particularly to an electrode system and method for electrically stimulating neurological tissue.
Normal physiologic function of many body tissues and structures depends on the transmission of electrical or electrochemical energy along discrete pathways. Numerous disorders and disease processes arise because of a dysfunction in normal electrical or electrochemical transmission in these tissues.
Various tissues and structures in the body may be artificially stimulated for purposes of enhancing, impeding, or modifying pathological physiologic function. Tissues in the nervous system are especially amenable to such stimulation by virtue of their inherent electrical and electrochemical properties. Physiologic function of nervous system tissue primarily requires the propagation of electrical energy along cell membranes and the release of intracellular chemical packets, which allows intracellular and intercellular communication. The effects of drugs and medications on nervous tissue generally depend on their actions on these processes. However, the use of medications is problematic. Virtually all medications have unwanted side effects, some serious or even fatal. Medications are costly and often require monitoring with periodic laboratory tests. Medication is also often inconvenient to take, especially when more than one daily dose is required. Poor patient compliance with medication is known to be a common reason for medication failure. Even when medications are taken as directed, they may fail to achieve the desired purpose.
Electrodes have been implanted in body tissues to act as modulators of such conditions as epilepsy, movement disorders and chronic pain. The use of such devices has been constrained by several factors, such as difficulty in placement (often requiring dangerous invasive procedures), the inconvenience or impracticality of size, the need for implantable power supplies and the necessity for power supply replacement.
Epilepsy is a pathological condition in which sudden abnormal discharges of electrical activity occur in various sites in the brain. These discharges tend to become hypersynchronous. Abnormal electrical activity may arise from single or multiple foci in the brain. Such activity may affect only circumscribed areas of brain tissue, or it may propagate and affect surrounding brain areas in a more widespread or even generalized fashion. Depending on the location and magnitude of such activity, clinical seizures may occur. Manifestations of seizures include uncontrollable movement of various body parts, abnormal sensations or perceptions or loss or alteration of content of consciousness. In addition to interfering with the normal function of the individual, seizures may result in serious injury or even death. It is known that stimulation of certain brain areas (including but not limited to the basal ganglia and cerebellum) by artificial means may act to inhibit the occurrence or propagation of abnormal electrical activity. Heretofore, such stimulation has been achieved by use of invasive electrodes requiring direct connection to a power source.
A number of pathologic conditions known as movement disorders may arise in the nervous system. These disorders may be caused by trauma, stroke, infection, toxins or unknown factors. This group of disorders includes Parkinson""s Disease (primary and secondary forms), Tourette""s Syndrome, Huntington""s Disease, various tremors (resting, postural and intention types), hemiballismus, various tics and several degenerative diseases. Effects of these conditions include excessive motor activity, inhibition of normal motor activity and abnormalities of muscle tone. These manifestations may range in severity from being simply embarrassing to being incapacitating. Attempts to ameliorate these disorders include the use of medications (which are problematic as discussed above) and various surgical procedures (which are irreversible and pose significant risks). It is known that artificial electrical stimulation of certain brain areas, particularly structures in the basal ganglia or thalamus, may reduce clinical manifestations of these disorders. Such stimulation requires the use of implantable electrode devices coupled with power sources.
Artificial electrical stimulation of the nervous system has also been used to treat conditions of chronic pain. This requires the use of implantable electrode devices connected to power sources.
In addition to the foregoing considerations, it is reasonable to suppose that other disorders of nervous system function (such as behavioral or psychiatric disorders) which have been amenable to pharmacological or surgical treatment might also respond to artificial electrical stimulation of nervous system structures.
Techniques for excitation of neurological tissue are known in the art. In U.S. Pat. No. 5,713,922, by King, entitled xe2x80x9cTechniques For Adjusting The Locus Of Excitation Of Neural Tissue In The Spinal Cord Or Brain, xe2x80x9d issued Feb. 3, 1998, one such technique is described where two anodes and a cathode are implanted into neurological tissue. Hardwired to the electrodes is a fully implanted or partially implanted electrical pulse generator. Electrical pulses from the generator are applied to the electrodes and the signal produced across each anode cathode pair is used to stimulate the neurological tissue of interest. A remotely located programmer allows an attendant to adjust the settings of the electrical pulse generator by radio frequency communication. However, these and other known neurological stimulation techniques are hampered by size, power, and communication constraints, among other things.
The present invention disclosed and claimed herein comprises, in one aspect thereof, a ball semiconductor system for stimulating a mass of nervous system tissue in a body for therapeutic purposes. The semiconductor ball adaptable to be embedded in the mass of nervous system tissue, and which ball semiconductor comprises a cathode and an anode electrode pair, and a receiver for wirelessly receiving electrical pulses for application to the electrode pair. A remote electrical pulse system communicates with the semiconductor ball and comprises a generator for generating the electrical pulses, and a transmitter for wirelessly transmitting the generated electrical pulses to the receiver of the semiconductor ball. The electrical pulses are applied to the electrode pair to cause the mass of nervous system tissue to become stimulated to therapy a pathological condition.